additives feature | PVC stabilizers
The use of lead-based stabilizers is due to end in the EU this year. The graph also shows the corresponding growth in calcium-based stabilisers
Source: ESPA
on the use of methyl tins, but risk assessments have been carried out in recent years in the EU on several other organo-tins. As a result, some restrictions now apply to various uses of dibutyl and dioctyl tin (DBT, DOT). DBT compounds have not been allowed in articles for
supply to the general public since the beginning of 2012, with certain exceptions for a limited period. These included soft PVC profi les, PVC coated fabrics for outdoor applications, and outdoor rainwater pipes, gutters and fi ttings and covering material for roofi ng and facades. Those derogations expired at the begin- ning of this year. DOT is still permitted in many applications. Items excluded include gloves, footwear intended for skin contact, and wall and fl oor coverings. Octyl tins can still be used in a limited number of applications. “The situation is evolving,” says Cavallero.
Variation in stabilizer use around the world, according to type (2012 data)
“But it is important to understand that not all tin-based additives are the same. A lot of attention has been focused on tributyl tin, TBT, but this has never been used as a stabilizer in PVC, only as a pesticide in applications such as antifouling paints for ships. It is unfortunate that this acronym has been used in some circles to mean all organotins, which have various toxicological profi les.”
Green light for calcium and liquids
In the future, the large majority of PVC stabilizers are expected to be calcium-based. There are no known REACH registration issues for the main system components of such stabilizers. These stabilizers (Ca-Zn and Ca-organic) are principally used for food-contact and medical applications, as well as all lead replacement systems. In the EU, they account for over 70% of all PVC stabilizers.
Liquid mixed metal stabilizers are used principally
for fl exible PVC, calendered sheets and fl ooring, and accounted for around 10% of PVC stabilizers used in the EU last year. EPSA says that they have been almost totally reformulated in recent years owing to REACH and re-classifi cation of some components. The Liquid Mixed Metal Consortium completed the REACH registrations due in 2013 and is pursuing the work for the remaining ones for Tier 3 (substances used in low volumes that have to be registered by June 2018). “Stabilizer producers have invested considerably in time and resources to develop alternatives to lead-based systems,” says Cavallero. “The close collaboration of
Source: Reagens
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COMPOUNDING WORLD | June 2015
www.compoundingworld.com
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